Unmanned Aerial Vehicle Sling Load

ABSTRACT

Example methods and systems for coupling and controlling transport of cargo using an unmanned aerial vehicle (UAV) are provided, comprising coupling at least one electronically-controllable attachment device positioned on an underside of the UAV to a sling cable, the sling cable being secured to the cargo. The UAV flies to a predetermined area above the cargo, and responsive to determining that the UAV is positioned within the predetermined area, the UAV elevates above the initial operating height to lift the cargo and navigates to a target location.

FIELD

The present disclosure generally relates to systems and methods fortransporting sling-loaded cargo, and more particularly to transportingsling-loaded cargo via an unmanned aerial vehicle (UAV).

BACKGROUND

It is often desirable to utilize aerial vehicles to transport cargo tovarious destinations. Such aerial vehicles, for example helicopters orother multi-rotor rotorcraft, connect an external load, such as cargo,to a sling that is attached to the aerial vehicle for lift and transportof the cargo. The sling comprises a line, such as a cable, that can varyin length, often up to 100 feet or more. The cargo can likewise vary inshape, size, and weight.

Currently, manual operation is required to attach and detach a slingcable to cargo for transport. A pilot of the aerial vehicle operatescontrols to position the aerial vehicle in a desired location withrespect to the cargo, and a ground crew external to the aerial vehiclemanipulates a load-engaging device to manually attach the cargo to thesling cable or to disengage the cargo from the sling cable.

With the increased use of unmanned aerial vehicles, a system and processto connect a sling line to a cargo and successfully transport the cargoduring a flight operation without human assist is desired.

SUMMARY

In one example, a method for transporting sling-loaded cargo using anunmanned aerial vehicle (UAV) is described. The method comprisesreceiving instructions at the UAV to transport the cargo to a targetlocation, coupling at least one electronically-controllable attachmentdevice positioned below an underside of the UAV to a first portion of asling cable, the sling cable having a predetermined length and a secondportion of the sling cable being secured to the cargo, and operating atleast four laterally-arranged rotors to cause the UAV to take-off andnavigate to (i) a position within a predetermined area above the cargoand (ii) an initial operating height, the initial operating height beingless than the predetermined length of the cable such that the UAV doesnot support the cargo. The method further comprises determining that theUAV is positioned within the predetermined area above the cargo, andresponsive to determining that the UAV is positioned within thepredetermined area, operating the at least four laterally-arrangedrotors to elevate the UAV above the initial operating height to lift thecargo and controlling the UAV to navigate to the target location.

In another example, a transport system is provided. The transport systemcomprises a UAV having at least four laterally-arranged rotors, one ormore sensors on the UAV configured to detect an angular position ofcargo relative to an underside of the UAV, an attachment device affixedto the underside of the UAV and configured to releasably couple to afirst portion of a cable having a predetermined length and being securedto the cargo at a second portion of the cable.

The system further comprises a control system for controlling transportof the cargo, comprising one or more processors configured to executeinstructions stored in memory to perform functions of: opening aretaining latch on the attachment device to receive the first portion ofthe cable, closing the retaining latch to couple the first portion ofthe cable to the attachment device, operating the at least fourlaterally-arranged rotors to cause the UAV to elevate to an initialoperating height, the initial operating height being less than thepredetermined length of the cable such that that UAV does not supportthe cargo, determining, via the one or more sensors, that the UAV ispositioned within a predetermined region above the cargo, and responsiveto determining that the UAV is positioned within the predeterminedregion above the cargo, operating the at least four laterally-arrangedrotors to elevate the UAV to a second height that is greater than theinitial operating height and controlling the UAV to navigate to a targetlocation.

In another example, a control system for controlling transport of acargo is provided. The control system comprises one or more processorsconfigured to execute instructions stored in memory to perform functionsof coupling at least one electronically-controllable attachment devicepositioned below an underside of the UAV to a first portion of a slingcable, operating at least four laterally-arranged rotors to cause theUAV to elevate to an initial operating height, the initial operatingheight being less than a predetermined length of the sling cable suchthat the UAV does not support the cargo, determining that the rotorcraftis positioned within a predetermined area above the cargo, andresponsive to determining that the UAV is positioned within apredetermined area above the cargo, operating at least fourlaterally-arranged rotors to cause the UAV to take-off and navigate to(i) a position within a predetermined area above the cargo and (ii) aninitial operating height, the initial operating height being less thanthe predetermined length of the sling cable such that the UAV does notsupport the cargo.

In a further example, a cargo attachment system for a UAV having atleast four laterally-arranged rotors is provided. The system comprises asupport beam structure comprising a plurality of support beams, at leastone of the plurality of support beams being affixed to an underside ofthe UAV, the support beam structure having a length projectingdownwardly from the underside of the UAV that is less than a length ofthe landing gear structure, wherein at least one of the plurality ofsupport beams projects away from the landing gear structure, and anattachment device coupled to at least one of the plurality of supportbeams, the attachment device being electrically controllable.

In another example, a UAV is provided. The UAV comprises a rotorcrafthaving at least four laterally-arranged rotors, a landing gear structureaffixed to an underside of the UAV, a support beam structure comprisinga plurality of support beams affixed to the underside of the UAV, thesupport beam structure having a length projecting downwardly from theunderside of the UAV that is less than a length of the landing gearstructure, wherein at least one of the plurality of support beamsprojects away from the landing gear structure, and an attachment devicecoupled to at least one of the plurality of support beams, theattachment device being electrically controllable.

In another example, a method of attaching a sling-loaded cargo to a UAVis provided. The method comprises electrically controlling a latch on anattachment device to open the latch, the attachment device being fixedto a support structure having a length projecting downwardly from anunderside of the UAV that is less than a length of the landing gearstructure, receiving a first portion of a cable at the attachmentdevice, and electrically controlling the latch to close the latch tosecure the first portion of the cable to the attachment device.

The features, functions, and advantages that have been discussed can beachieved independently in various examples or may be combined in yetother examples further details of which can be seen with reference tothe following description and drawings.

BRIEF DESCRIPTION OF THE FIGURES

The novel features believed characteristic of the illustrative examplesare set forth in the appended claims. The illustrative examples,however, as well as a preferred mode of use, further objectives anddescriptions thereof, will best be understood by reference to thefollowing detailed description of an illustrative example of the presentdisclosure when read in conjunction with the accompanying drawings,wherein:

FIG. 1A illustrates a transport system for transporting cargo, accordingto an example implementation.

FIG. 1B illustrates a perspective view of the transport system of FIG.1A, according to an example implementation.

FIG. 2 illustrates an enlarged view of the attachment structure for thesystem of FIG. 1A, according to an example implementation.

FIG. 3 illustrates an example attachment device for use with the systemof FIG. 1A, according to an example implementation.

FIG. 4A illustrates an example attachment system to attach a cable tothe attachment device of FIG. 3, according to an example implementation.

FIG. 4B illustrates an example attachment system to attach a cable tothe attachment device of FIG. 3, according to an example implementation.

FIG. 4C illustrates an example attachment system to attach a cable tocargo for use with the system of FIG. 1A, according to an exampleimplementation.

FIG. 5 illustrates a block diagram of an example of the system of FIG.1A, according to an example implementation.

FIG. 6 illustrates a flowchart of an example of a method fortransporting sling-loaded cargo using a UAV, such as the UAV of thesystem of FIG. 1A, according to an example implementation.

FIG. 7 illustrates another method for use with the method shown in FIG.6, according to an example implementation.

FIG. 8 illustrates another method for use with the method shown in FIG.6, according to an example implementation.

FIG. 9 illustrates another method for use with the method shown in FIG.8, according to an example implementation.

FIG. 10 illustrates another method for use with the method shown in FIG.6, according to an example implementation.

FIG. 11 illustrates another method for use with the method of FIG. 6,according to an example implementation.

FIG. 12 illustrates another method for use with the method of FIG. 11,according to an example implementation.

FIG. 13 illustrates a flowchart of an example of a method for attachinga sling-loaded cargo to a UAV, such as the UAV of the system of FIG. 1A,according to an example implementation.

FIG. 14 illustrates another method for use with the method of FIG. 13,according to an example implementation.

FIG. 15 illustrates another method for use with the method of FIG. 13,according to an example implementation.

FIG. 16A illustrates a mission operation for attaching and transportingcargo of the system of FIG. 1A, according to an example implementation.

FIG. 16B illustrates a mission operation in which a manual trigger isused for detaching cargo of the system of FIG. 1A, according to anexample implementation.

FIG. 16C illustrates a first contingency operation for detaching cargoof the system of FIG. 1A, according to an example implementation.

FIG. 16D illustrates a second contingency operation for detaching cargoof the system of FIG. 1A, according to an example implementation.

DETAILED DESCRIPTION

Disclosed examples will now be described more fully hereinafter withreference to the accompanying drawings, in which some, but not all ofthe disclosed examples are shown. Indeed, several different examples maybe described and should not be construed as limited to the examples setforth herein. Rather, these examples are described so that thisdisclosure will be thorough and complete and will fully convey the scopeof the disclosure to those skilled in the art.

Examples, methods, and systems are described to attach a sling-loadedcargo to an aerial vehicle and to then transport and release the cargo.The system and methods described herein provide for electrical controlof attachment and release of a cargo from an aerial vehicle. To thisend, an attachment mechanism which is in electrical communication with acontrol unit associated with the aerial vehicle is controlled to openand close, effectively releasing or retaining a sling cable therein, thecable also being secured to a cargo. The system and methods provide fora more streamlined transport process and do not require time andphysical efforts of personnel for positioning, attachment, and/orrelease of the cargo from the aerial vehicle. The systems and methodsprovide an improved process for attaching a sling-loaded cargo to anaerial vehicle and for autonomously controlling the aerial vehicle totake-off and then lift the cargo. Additionally, the capability forremote control allows for improved decisions to be made with respect tolanding of cargo and/or a UAV transporting cargo in contingentscenarios, wherein for a variety of reasons a change from apredetermined flight trajectory may occur.

Referring to FIG. 1A, a transport system 100 to transport cargo 102 isillustrated, according to an example implementation.

The transport system 100 includes an unmanned aerial vehicle (UAV) 104comprising a support beam structure 110, a landing gear structure 120,at least one electrically controllable attachment device 130, and twocables 140. In operation, the UAV 104 is utilized to lift and transportcargo.

The UAV 104 includes a main housing 107 and a propulsion unit mounted onthe main housing 107 for propelling through an environment. Thepropulsion unit may be an internal combustion engine, an electricbattery, or a hybrid engine such as an electric-internal combustionengine. The UAV 104 further comprises one or more rotor systems coupledto the housing and operatively connected to the propulsion unit. In oneexample embodiment, a rotor system comprising one or more propellerblades is attached to the main housing 107 via an arm extending from thehousing. Within examples, the UAV 104 includes at least fourlaterally-arranged rotors. The laterally-arranged rotors may be rotorassemblies that are operatively supported by and spaced around the mainhousing 107 of the UAV. In some example embodiments, the UAV 104comprises four laterally-arranged rotors 105. FIG. 1A shows two of foursuch rotors in an aft view of the UAV 104. FIG. 1B illustrates aperspective view of the transport system of FIG. 1A, and shows all ofthe rotors 105 of UAV 104. In other examples, more or fewer rotors maybe present. The support beam structure 110 and the landing gearstructure 120 are both shown to be connected to an underside 106 of themain housing 107 of the UAV 104.

FIG. 1B also shows an angle 194, formed between an axis of rotation anda reference point on cargo 102. As the cargo 102 sways or moves during aflight, the angle 194 will vary.

In one example, the UAV 104 is designed to carry cargo of up to about250 lbs. In other examples, the UAV 104 is designed to carry cargo ofgreater weight, such as 300 lbs. Other examples are possible as well.

The landing gear structure 120 enables the UAV 104 to take off and landon ground, and comprises a plurality of legs 122, each of which areconnected to the underside 106 of the UAV 104 and extend downward fromthe underside 106, toward the ground; each of the legs 122 may have aground engaging mechanism, such as wheels, at a lower end of the leg122. Additional supports 124 may affix the legs 122 to the UAV 104.

The support beam structure 110, like the landing gear structure, isaffixed to the underside 106 of the UAV and extend downward and awayfrom the underside 106, toward the ground. In some embodiments, thesupport beam structure 110 attaches directly to a surface on theunderside 106 of the UAV. In other embodiments, the support beamstructure 110 may attach to the landing gear structure 120 or anotherintermediary structure that is in turn attached to the UAV 104.

The at least one electronically-controllable attachment device 130 ispositioned below the underside 106 of the UAV 104. The example of FIG.1A includes two electronically-controllable attachment devices 130. Theelectronically-controllable attachment devices 130 are connected to thesupport beam structure 110 and serve to each releasably couple a cable140 to the support beam structure 110. The electronically-controllableattachment devices 130 are configured to operate when the UAV 104 is onthe ground. An example electronically-controllable attachment device 130is described with reference to FIG. 3.

The cables 140 may comprise sling cables or payload suspension cables.In one example embodiment, the length of each of the cables 140 is atleast 25 feet. In some example embodiments, the length of each of thecables 140 is in the range of 25 to 150 feet, the diameter of each ofthe cables 140 is about 0.172 inches, and the cables 140 each have aminimum spliced strength of 3,780 lbs. In some embodiments, each of thecables 140 has a maximum working load of 840 lbs.

The UAV 104 is configured to lift and transport cargo via the cables140. Each cable 140 is connected to the support beam structure 110 byway of a first anchor point of the cable 140 being coupled to arespective attachment device 130. The cable 140 has a second anchorpoint that is coupled to the cargo 102. During transit, cargo can becomeunstable and swing in any given direction. In some cases, cargo canswing high enough to become entangled in the landing gear structure,rotorcraft airframe, and/or rotors. Thus additionally, as shown in FIG.1A, lateral arresting cable portions 150 may be provided. The lateralarresting cable portions 150 extend between a first cable 140 and asecond cable 140 to prevent interference of the cables 140 with thelanding gear structure 120, or other parts of the UAV 104 that mayprotrude into either the first cable 140 or the second cable's 140unrestricted range of motion.

The lateral arresting cable portions 150 extend between the cables 140,from a first point of attachment on one cable (located near theattachment device 130) to a second point of attachment on another cable.The second point of attachment is located below the landing gearstructure 120 to limit movement of the sling-loaded cargo 102 operatingenvelope to prevent interference with the landing gear structure 120. Inone example embodiment, the second point of attachment is positionedabout 2 feet below the landing gear structure 120. In another exampleembodiment, the second point of attachment is positioned about 5 feetbelow the landing gear structure 120. Further example distances may beenvisioned.

In some embodiments, the attachment device 130 is attached to at leastone of the plurality of support beams 111, 112, 113, 114 at a positionsuch that one of the cables 140 coupled to the attachment device 130 iscapable of reaching a maximum threshold angle without interfering withthe landing gear 120 to which the support beam structure 110 isattached. For instance, the cables 140 may be limited to an operatingenvelope in which the cables 140 are prevented from interfering with thelanding gear structure 120. In example embodiments, the position of theattachment device 130 and the points of attachments of the lateralarresting cable portions 150 are selected such that the cables 140 arelimited to an operating envelope in which the cables 140 are preventedfrom interfering with the landing gear structure 120.

One or more sensors 160 may be attached to the UAV 104 and may bepositioned to observe the region in which the cargo is being lifted andtransported. The sensors 160 may include sensors useful for identifyingobjects and aiding in navigation, such as optical sensors (e.g., camera,infrared, RGB camera), acoustic sensors, radar sensors, and amultifunction light detection and ranging (LIDAR) system. Opticalsensors may capture images nominally at a set frame capture rate. Thesensors 160 may further include a rotary variable inductance transducer(RVIT) to detect an angular position of the cargo 102 relative to theunderside 106 of the UAV 104.

Examples of computational resources on the UAV 104 may include, but arenot limited to, built-in control systems for receiving and storinginformation and executing instructions to control the attachment device130, guidance systems to perform low-level human pilot duties such asspeed and flight-path stabilization, and scripted navigation functions.The UAV 104 may also include a communication interface for receivinginstructions from a remote control system.

In some examples, the UAV 104 is configured to navigate to a targetlocation, such as the target location 416 shown in FIG. 16A, to make adetermination that the UAV 104 is hovering above the target location,and then to actuate its release mechanism on the attachment device 130to open a pathway to the opening 132 to release the cable 140 holdingthe cargo 102 from its connection to the UAV 104.

FIG. 2 illustrates an enlarged view of two support beam structures 110for the transport system 100 of FIG. 1A, according to an exampleimplementation. As shown in FIG. 2, an aft view looking up towards theunderside 106, each support beam structure 110 comprises a plurality ofsupport beams, including a first or an upper support beam 112, a secondor a lower support beam 114, an air vehicle lug attachment 116, alanding gear lug attachment 118, and a link assembly 121. The airvehicle lug attachment 116 is affixed to a surface on the underside 106of the UAV 104. The upper support beam 112 is connected to the lugattachment 116, and may comprise an alignment feature 117 defining alumen 119, through which an electric wire 115 extends. The electric wire115 has a first end 191 and a second end 192 and an intermediate portion193 between the first end 191 and the second end 192; the intermediateportion 193 extending through the lumen 119 of the alignment feature117, and the second end 192 of the electric wire 115 connects to theattachment device 130. The electric wire 115 serves to electricallycouple the attachment device 130 to a controller on the UAV 104.

The lower support beam 114 serves to further secure the upper supportbeam 112 and the attachment device 130 to the UAV 104. To that end, afirst end of the lower support beam 114 is connected to the uppersupport beam 112 and a second end of the lower support beam 114 isconnected to the UAV 104 or to a structure affixed to the UAV 104.Multiple lower support beams 114 may be present to aid in securing thesupport beam structure 110; FIG. 2, for example, shows three lowersupport beams 111, 113, 114 for each support beam structure 110. Thelanding gear lug attachments 118 affix the second end of each of thelower support beams 114 to the landing gear structure 120 in FIG. 2.Both the lower support beams 114 and the upper support beams 112 may beformed from a high strength material, for example, from a metal such assteel, aluminum, or from a combination of metal and composite materials.Other high strength materials may also be contemplated.

The link assembly 121 secures the attachment device 130 to the supportbeam structure 110. The support beam structure 110 has an overall length180 that is less than a length of a landing gear structure 120 of theUAV 104, the support beam structure projecting downwardly in direction182 from the underside 106 of the UAV 104 and away in direction 184 fromthe landing gear structure 120. The overall length 180 is such that thesupport beam structure 110 does not extend below the landing gearstructure 120 during flight of the UAV 104. One or more of the pluralityof support beams of the support beam structure 110 project away from thelanding gear structure 120 (e.g., in the direction 184 away from thelanding gear structure). For instance, as shown in FIG. 2, lower supportbeams 113 and 114 project away from the landing gear structure 120. Thisprojection away from the landing gear structure 120 helps to provide anoperating envelope for the cable 140 such that the cable 140 does notinterfere with the landing gear structure 120 during transport of thecargo 102.

FIG. 3 illustrates an example attachment device 130 for use with thesystem of FIG. 1A, according to an example implementation. In FIG. 3,the attachment device 130 comprises a latch which is electricallycontrollable to open and close, thus controlling access to an opening132 through which a cable or component affixed to a cable can beinserted.

The attachment device 130 may be formed from a high strength metal, suchas stainless steel, and may include a cam and spring. The cam may beelectrically actuated and comprise discrete position sensingcapabilities, for example having the capability to detect whether thelatch is an open state or closed state. In some example embodiments, thelatch in its closed position may be able to retain and hold a tensileload of up to about 1100 lbs. The latch may be released, opened, orotherwise retracted to allow access into the opening 132, or the latchmay be closed to shut off such access. A mechanical override trigger 134may additionally be provided on the attachment device 130, which can bemanipulated to manually move the latch, thereby opening or closingaccess to the opening 132. An actuated hook or solenoid-pin and clevisdevice may be used in an alternative embodiment to serve the retentionand release functions discussed herein. Further, any other form ofmanipulatable release mechanism may be envisioned. Bolts 136 serve toaffix a link assembly, such as the link assembly 121 of FIG. 2, to theattachment device 130.

The electrical actuation of the latch on the attachment device 130 maybe remotely controlled. Instructions to open or close the latch may thusbe provided by a control unit on the UAV 104, such as the control unit170, or by a remote control system, such as the remote control system175 discussed with reference to FIG. 5. In this manner, instructions maybe sent to open the latch on the attachment device 130, therebyreleasing a cargo from a UAV during a mission profile or a contingencyaction. The attachment device 130 may further be configured to sendsignals to the control unit 170 or a remote control system such asremote control system 175 indicating whether the attachment device isopened or closed. Alternatively, an operator may manually commandrelease of the sling-loaded cargo. A fault may be asserted by thecontrol unit 170 or remote control system should a command be sent toopen or close the attachment device and thereafter the control unit doesnot receive an indication that the status of the attachment device hasbeen changed accordingly. Additionally, a release signal (whethermanually by an operator or as a function performed by a processor) maybe required to issue constantly for a predetermined period of timebefore the control unit executes instructions to electrically activatethe release. The control unit may then hold an “open” command for apredefined time period before issuing a “rest” or “closed” command(wherein the latch closes). Example flight scenarios are described withreference to FIGS. 16A-D.

FIG. 4A illustrates an example attachment system to attach a cable 140to the attachment device 130 of FIG. 3, according to an exampleimplementation. In FIG. 4A, a cable attachment 142 at an end of thecable 140 serves as a first anchor point for the cable 140. The cableattachment 142 routes or extends through a hole in a latch striker 144,and the T-shaped connector in turn is positioned within the opening 132.In alternative embodiments, the shape of the cable attachment 142 mayvary, as may the shape of the latch striker 144. The latch striker 144ensures repeatable and consistent release operation for when the latchactuates, serving to eject the striker in a latch open state. The latchstriker 144 also serves to protect the cable 140 from wear or damage byisolating the cable 140 from the latch itself In FIG. 4A, the latchstriker 144 and the cable attachment 142 are integral, forming part ofan assembly. The latch striker 144 may comprise titanium, steel, oraluminum, in example embodiments. Other materials may be contemplated aswell.

FIG. 4B illustrates an example attachment system to attach a cable 140to the attachment device 130 of FIG. 3, according to an exampleimplementation. In FIG. 4B, an additional attachment component isprovided; namely, a loop connector 145, which connects to the latchstriker 144 via a bolt or other rod-shaped fastener that extends througha hole in the latch striker 144. The cable attachment 142 is thencoupled to the loop connector 145 by being positioned through a lumen ofthe loop connector 145.

FIG. 4C illustrates an example attachment system to attach a cable 140to cargo 102 for use with the system of FIG. 1A, according to an exampleimplementation. The attachment system shown in FIG. 4C is similar tothat of FIG. 4B, wherein a second cable attachment 146 of the cable 140serves as a second anchor point for the cable 140, the second cableattachment 146 then being coupled to a loop connector 145 by extendingthrough a hole of the loop connector 145. The loop connector 145 may becoupled to the cargo via a bolt or other rod that extends through a holein the cargo structure.

FIG. 5 illustrates a block diagram of an example of the transport system100 of FIG. 1A, according to an example implementation.

The UAV 104 includes a control unit 170, which is operatively coupled toa propulsion unit 172, a navigation module 174, the attachment device130, the one or more sensors 160, and an image processor 177. A remotecontrol system 175 may communicate with the control unit 170 of the UAV104.

The control unit 170 controls operation of the UAV 104. As used herein,the term “control unit” may include any processor-based ormicroprocessor-based system including systems using microcontrollers,logic circuits, and any other circuit or processor including hardware,software, or a combination thereof capable of executing the functionsdescribed herein. For example, each of the control unit 170 may be orinclude one or more processors 171 that are configured to controloperation of the UAV 104.

The control unit 170, for example, is configured to execute a set ofinstructions that are stored in one or more storage elements, or memory,173 in order to process data. The memory 173 may be in the form of aninformation source or a physical memory element. The set of instructionsmay include various commands that instruct the control unit 170 toperform specific operations such as the methods and processes of thevarious examples of the subject matter described herein. The set ofinstructions may be in the form of a software program. Software may bestored on a tangible and non-transitory computer readable storagemedium, such as a computer hard drive, ROM, RAM, or the like.

Thus, as described with reference to FIGS. 1-5, a system for attachingand facilitating transport of sling-loaded cargo is achieved. In someimplementations, electrical control of attachment and release of a cable(that is attached to cargo) from a UAV is achieved, which provides for amore streamlined transport process and does not require time andphysical efforts of personnel. Additionally, remote control allows forimproved decisions to be made with respect to landing of cargo and/or aUAV transporting cargo in contingent scenarios, wherein for a variety ofreasons a change from a predetermined flight trajectory occurs.

FIG. 6 shows a flowchart of an example of a method 200 for transportingsling-loaded cargo using a UAV. Method 200 shown in FIG. 6 presents anexample of a method that, for example, could be used with the transportsystem 100 shown in FIGS. 1A-B, for example. Method 200 includes one ormore operations, functions, or actions as illustrated by one or more ofblocks 202-210. Although the blocks are illustrated in a sequentialorder, these blocks may also be performed in parallel, and/or in adifferent order than those described herein. Also, the various blocksmay be combined into fewer blocks, divided into additional blocks,and/or removed based upon the desired implementation.

It should be understood that for this and other processes and methodsdisclosed herein, flowcharts show functionality and operation of onepossible implementation of present examples. Alternative implementationsare included within the scope of the examples of the present disclosurein which functions may be executed out of order from that shown ordiscussed, including substantially concurrent or in reverse order,depending on the functionality involved, as would be understood by thosereasonably skilled in the art.

At block 202, the method 200 includes receiving instructions at a UAV104 to transport sling-loaded cargo 102 to a target location.Sling-loaded means that the cargo 102 is attached to the UAV 104 via asling cable. In some embodiments, the UAV 104 may receive theinstructions from a remote control system such as the remote controlsystem 175 of FIG. 5. The UAV 104 may be docked at a storage location orotherwise grounded on land, and upon receiving the instructions, the UAV104 launches into the air and flies toward a region containing the cargo102.

At block 204, the method 200 includes coupling at least oneelectronically-controllable attachment device positioned below anunderside of the UAV 104 to a first portion 143 of a sling cable 140.The electrically-controllable attachment device may be the attachmentdevice 130 described with reference to FIGS. 1A-4B, and may be coupledto the first portion 143 of the sling cable 140 as described withreference to FIGS. 4A-B, for example.

The sling cable 140 has a predetermined length 141, and a second portion147 of the sling cable 140 is secured to the cargo 102 at a first anchorpoint of the cargo 102. The second portion 147 of the sling cable 140may comprise an attachment component at a second anchor point, such asthe cable attachment 142 of FIG. 4C, which may be coupled to the cargo102 as described with reference to FIG. 4C.

At block 206, the method 200 includes operating at least fourlaterally-arranged rotors to cause the UAV 104 to take-off and navigateto (i) a position within a predetermined area above the cargo, and (ii)an initial operating height 413, as shown in FIGS. 16A-D. The initialoperating height 413 is less than the predetermined length of the cablesuch that the UAV 104 does not support the cargo 102.

At block 208, the method 200 includes determining that the UAV 104 ispositioned within the predetermined area above the cargo 102. The UAV104 may initially be positioned adjacent the cargo on land duringattachment of the cargo 102 to the UAV 104, and at least fourlaterally-arranged rotors may be operated to elevate the UAV 104initially vertically in an upward direction followed by flying the UAV104 in a horizontal or angled direction toward the predetermined area.The predetermined area may be located directly above the cargo such thatthe UAV 104 hovers directly above the cargo at the initial operatingheight.

At block 210, the method 200 includes responsive to determining that theUAV 104 is positioned within the predetermined area, operating the atleast four laterally-arranged rotors to elevate the UAV 104 above theinitial operating height to lift the cargo 102 and controlling the UAV104 to navigate to the target location.

FIG. 7 shows another method for use with the method 200 shown in FIG. 6,according to an example implementation. In FIG. 7, at block 212, themethod includes determining that the cargo 102 is at the targetlocation. At block 214, the method includes responsive to thedetermination that the cargo 102 is at the target location, releasingthe first portion 143 of the cable 140 from the at least one attachmentdevice 130. The first portion 143 of the cable 140 may be released froman attachment device, such as the attachment device 130 described withreference to FIGS. 3-4B, for example. At block 216, the method includesproceeding to fly to and land at a target location.

Releasing the first portion 143 of the cable 140 may comprise receivinga release command, either manually by an operator, or as a functionperformed by the control unit 170 or a remote control system. A releasecommand may issue constantly, for a predefined period of time, beforethe system electrically activates the latches on the attachment devices130 to open. In one example embodiment, the predefined period of timecomprises five seconds. In other example embodiments, the predefinedperiod of time may comprise an amount of time that is less or more thanfive seconds.

FIG. 8 shows another method for use with the method 200 shown in FIG. 6,according to an example implementation. In FIG. 8, at block 218, themethod includes defining a mission profile that comprises a plurality ofpredetermined contingency landing sites along a travel path to thetarget location. The predetermined contingent landing sites may eachcomprise a cargo recovery system. In the example embodiments shown inFIGS. 16C-16D, a plurality of contingent landing sites 440 are shown.

FIG. 9 shows another method for use with the method 200 shown in FIG. 6,according to an example implementation. In FIG. 9, at block 220, themethod includes determining to execute a contingent landing at one ofthe plurality of predetermined contingent landing sites. At block 222,the method includes responsive to the determination, actuating the atleast one attachment device to open a closure on the at least oneattachment device, thereby decoupling the first portion 143 of the cable140 from the at least one attachment device. The closure may comprise alatch, in one example embodiment as described with reference to FIG. 3,and decoupling the first portion 143 of the cable 140 may operate asdescribed with reference to FIGS. 4A-B. At block 224, the methodincludes proceeding to fly to and land at the contingent landing site.

FIG. 10 shows another method for use with the method 200 shown in FIG.6, according to an example implementation. In FIG. 10, at block 226, themethod includes receiving information from the at least one attachmentdevice indicating whether the at least one attachment device 130 isopened or closed. The at least one attachment device may be configuredto send signals indicating an opened or closed state for the attachmentdevice 130. Such signals may be received at the control unit 170 of theUAV 104 or at a remote system, such as the remote control system 175 ofFIG. 5.

FIG. 11 shows another method for use with the method 200 shown in FIG.6, according to an example implementation. In FIG. 11, at block 228, themethod includes detecting, via at least one sensor, an angular positionof the cargo relative to the underside of the UAV.

FIG. 12 shows another method for use with the method 200 shown in FIG.6, according to an example implementation. In FIG. 12, at block 230, themethod includes calculating an angular position of the cargo relative tothe UAV based on an angle of the cable. The calculation may comprisedetermining a reference point on the cargo 102, which can then be usedto describe the angular motion of the cargo 102. The angular position ofthe reference point is the angle 0, shown as angle 194 in FIG. 1B,formed between an axis of rotation and the reference point. In someexamples, angular displacement of the cargo may be calculated anddescribed using rotation matrices or Euler angles.

FIG. 13 shows a flowchart of an example of a method 300 for attaching asling-loaded cargo to a UAV, such as the UAV of the system of FIG. 1A,according to an example implementation. In FIG. 13, at block 302, themethod includes electrically controlling a latch on an attachment device130 to open the latch, the attachment device being fixed to a supportstructure having a length projecting downwardly and outwardly from anunderside of the UAV that is less than a length of the landing gear. Insome embodiments, the latch and attachment device comprise the latch andattachment device 130 described with reference to FIG. 3.

At block 304, the method includes receiving a first portion 143 of acable 140 at the attachment device 130. In some embodiments, the firstportion 143 of the cable 140 is received at the attachment device 130 asdescribed with reference to FIGS. 4A-B.

At block 306, the method includes electrically controlling the latch toclose the latch to secure the first portion 143 of the cable 140 to theattachment device. A control unit, such as the control unit 170 or theremote control system 175 of FIG. 5, may execute instructions to the UAV104 to electrically control the latch to transition the latch to aclosed position.

FIG. 14 shows another method for use with the method 300 shown in FIG.13, according to an example implementation. In FIG. 14 at block 308, themethod includes electrically coupling the first attachment device andthe second attachment device to a controller on the UAV via one or moreelectric wires.

FIG. 15 shows another method for use with the method 300 shown in FIG.13, according to an example implementation. In FIG. 15 at block 310, themethod includes electrically controlling the latch to re-open the latchand release the first portion 143 of the cable 140 from the attachmentdevice 130.

FIG. 16A illustrates a mission operation for attaching and transportingcargo of the system of FIG. 1A, according to an example implementation.As shown in FIG. 16A, at a location 410, a UAV, such as the UAV 104 ofFIG. 1A, is positioned on the ground and is coupled to a cargo, such asthe cargo 102 of FIG. 1A. The cargo 102 is shown to be positioned withina takeoff stability device 402 that is on the ground in the example ofFIG. 16A, and the cargo 102 is coupled to the UAV 104 via a cable, suchas the cable 140 of FIG. 1A. A control module, such as the control unit170 or the remote control system 175 of FIG. 5, may receive apredetermined flight trajectory based on a set of flight planparameters. In response, the control unit 170 operates the rotors of theUAV 104 to move the UAV 104 along the determined flight trajectory. Theflight plan trajectory may include operating the UAV 104 to perform aload lift procedure, wherein the UAV 104 takes off, elevating to aninitial operating height 411, as well as navigating to a predeterminedarea above the cargo 102, as described in the method 200 of FIG. 6.

At location 410, the UAV 104 hovers at the initial operating height,which is less than the length of the cable 140 used to couple the cargo102 to the UAV 104, such that the UAV 104 does not support the cargo 102during take-off. Sensors, such as the sensors 160 described withreference to FIG. 1A, may be used to obtain and relay information to thecontrol unit 170 or the remote control system 175 concerning theposition of the UAV 104 relative to the cargo 102. The control unit 170then determines whether the UAV 104 is positioned within a predeterminedarea above the cargo 102, and if so, the UAV proceeds to elevate abovethe initial operating height, and fly along the planned flighttrajectory 412. The flight trajectory 412 includes a descent portion414, and at a target location 416 the UAV 104 returns to a flightposition that is lower to the ground, and which may be at the sameheight as or similar to the height of the UAV 104 at location 410. Forexample, when the UAV 104 is at the target location 416, the UAV 104 mayproceed to navigate to a position 430 above a cargo drop area 432 havinga cargo release height 434 that is less than the predetermined length141 of the sling cable 140. Once the UAV 104 is determined to be locatedat the position 430, the control unit 170 may execute instructions toperform a cargo set down procedure. The cargo set down procedurecomprises executing instructions to open the latch on the attachmentdevice 130 holding the cable 140, effectively releasing the cable 140and associated cargo 102 from the UAV 104. In some embodiments, thecargo 102 may be released to land on the ground, an airbag that ispositioned on the ground, or another landing mechanism configured tocushion the cargo 102. After releasing the cable 140 and cargo 102, theUAV 104 proceeds to navigate to a location suitable for landing.

In some embodiments, the control unit 170 is configured to control thelaterally-arranged rotors 105 to cause the airborne UAV 104 to descendtowards the target location 416 until one or more sensors determine thatthe cargo 102 has contacted the destination landing surface at targetlocation 416, and is further configured to control theelectronically-controllable attachment devices 130 to release the slingcable 140 such that the cargo 102 and sling cable 140 are detached fromthe UAV 104.

Optionally, the control unit 170 may be configured to receive a manualinput from an operator to maneuver the release of cargo in flight to adesignated cargo drop area. FIG. 16B illustrates a mission operation inwhich a manual trigger is used for detaching cargo of the system of FIG.1A, according to an example implementation. As shown in FIG. 16B, theUAV 104 initially couples to cargo 102, takes off, and elevates to aninitial operating height 413, similarly as described with reference toFIG. 16A. The UAV 104 then proceeds to elevate, flying along the plannedtrajectory 412. At any point during the planned trajectory 412, anoperator manually triggers a release mechanism to release the cable 140with attached cargo 102 from the attachment device 130; one example ofsuch a release action is shown at location 420. The cable 140 and thecargo 102 then descend to the ground, while the UAV 104 proceeds tonavigate in the air in accordance with the planned trajectory 412,descending in accordance with the descent portion 414 of the trajectory412 and hovering low to the ground, until the UAV 104 finally lands.

FIG. 16C illustrates a first contingency operation for detaching cargoof the system of FIG. 1A, according to an example implementation. Amission profile may be defined for a predetermined flight trajectorythat comprises a plurality of predetermined contingent landing sites 440along the travel path to the target location. The predeterminedcontingent landing sites 440 may each comprise a cargo recovery system.In some example embodiments, the cargo recovery system includes one ormore airbags. As shown in FIG. 16C, the UAV 104 initially couples to thecargo 102, takes off, and elevates to an initial operating height 413,similarly as described with reference to FIG. 16A. At some point duringthe planned trajectory, for example, at location 422, an abort toplanned zone signal is issued to the UAV 104, and the UAV 104 thenchanges course from the predetermined flight trajectory to fly moredirectly to a planned target location; this contingency trajectory isshown at path 424. In the scenario depicted in FIG. 16C, the UAV 104retains the cargo 102 until the UAV 104 reaches a low to the ground,hovering position above the planned target location, within which is acargo drop area, at which point the attachment device 130 releases thecable 140 with attached cargo 102; this release action is shown atlocation 420. The cable 140 and the cargo 102 then descend to theground, while the UAV 104 proceeds to navigate in the air in accordancewith the contingency trajectory, descending and hovering low to theground at the target location 416, which may be at the same height as orsimilar to the height of the UAV 104 at location 410. Once the UAV 104is positioned at the target location 416, the control unit 170 mayexecute instructions to open the latch on the attachment device 130holding the cable 140, effectively releasing the cable 140 andassociated cargo 102 from the UAV 104. After releasing the cable 140 andcargo 102, the UAV 104 proceeds to navigate to a location suitable forlanding.

FIG. 16D illustrates a second contingency operation for detaching cargoof the system of FIG. 1A, according to an example implementation. Asshown in FIG. 16D, the UAV 104 initially couples to the cargo 102, takesoff, and elevates to an initial operating height 413, similarly asdescribed with reference to FIG. 16A. At some point during thepredetermined flight trajectory, for example, at location 426, a landnow signal is issued to the UAV 104, and the UAV 104 then changes coursefrom the predetermined flight trajectory to fly more directly to theground; this contingency trajectory is shown at path 428. In thescenario depicted in FIG. 16D, the UAV 104 releases the cable 140holding the cargo 102 to deliver the cargo 102 to one of the contingentlanding sites 440 upon receipt of the land now signal, and proceeds tonavigate toward the nearest ground location 430 on which the UAV 104 cansuccessfully land. The cargo 102 is also shown as having landed at theone of the contingent landing sites 440.

Within examples, methods and system described herein can be used toremotely attach sling-loaded cargo to a UAV and thereafter release thecargo, either upon completion of a mission profile or in a contingencyaction. Such methods and systems render attachment and releaseself-operable so that it is not necessary to employ a ground crew tomanipulate the latch to engage or disengage from a load. Examples of thedisclosure may find use in a variety of potential applications,particularly in the transportation industry and for any mission in whichtransporting sling-loaded cargo is desired.

In other embodiments, the methods and systems described herein wouldalso be beneficial for use with a manned aerial vehicle, or where agrounds crew is present to facilitate attachment or detachment of cargoto a cable.

As used herein, the term “about” includes aspects of the recitedcharacteristic, parameter, or value allowing for deviations orvariations, including for example, tolerances, measurement error,measurement accuracy limitations and other factors known to skill in theart, and also ranges of the parameters extending a reasonable amount toprovide for such variations.

The description of the different advantageous arrangements has beenpresented for purposes of illustration and description, and is notintended to be exhaustive or limited to the examples in the formdisclosed. Many modifications and variations will be apparent to thoseof ordinary skill in the art. Further, different advantageous examplesmay describe different advantages as compared to other advantageousexamples. The example or examples selected are chosen and described inorder to explain the principles of the examples, the practicalapplication, and to enable others of ordinary skill in the art tounderstand the disclosure for various examples with variousmodifications as are suited to the particular use contemplated.

What is claimed is:
 1. A method for transporting sling-loaded cargousing an unmanned aerial vehicle (UAV), the method comprising: receivinginstructions at the UAV to transport the cargo to a target location;coupling at least one electronically-controllable attachment devicepositioned below an underside of the UAV to a first portion of a slingcable, the sling cable having a predetermined length and a secondportion of the sling cable being secured to the cargo; operating atleast four laterally-arranged rotors to cause the UAV to take-off andnavigate to (i) a position within a predetermined area above the cargoand (ii) an initial operating height, the initial operating height beingless than the predetermined length of the cable such that the UAV doesnot support the cargo; determining that the UAV is positioned within thepredetermined area above the cargo; and responsive to determining thatthe UAV is positioned within the predetermined area, operating the atleast four laterally-arranged rotors to elevate the UAV above theinitial operating height to lift the cargo and controlling the UAV tonavigate to the target location.
 2. The method of claim 1, furthercomprising: determining that the cargo is at the target location;responsive to the determination that the cargo is at the targetlocation, releasing the first portion of the cable from the at least oneattachment device; and proceeding to fly to and land at the targetlocation.
 3. The method of claim 1, further comprising: defining amission profile that comprises a plurality of predetermined contingentlanding sites along a travel path to the target location, wherein thepredetermined contingent landing sites each comprise a cargo recoverysystem.
 4. The method of claim 3, further comprising: determining toexecute a contingent landing at one of the plurality of predeterminedcontingent landing sites; and responsive to the determination, actuatingthe at least one attachment device to open a closure on the at least oneattachment device, thereby decoupling the first portion of the cablefrom the at least one attachment device; and proceeding to fly to andland at the contingent landing site.
 5. The method of claim 1, furthercomprising: receiving information from the at least one attachmentdevice indicating whether the at least one attachment device is open orclosed.
 6. The method of claim 1, further comprising: detecting, via atleast one sensor, an angular position of the cargo relative to theunderside of the UAV, wherein the at least one sensor comprises a rotaryvariable inductance transducer (RVIT).
 7. The method of claim 6, furthercomprising: calculating an angular position of the cargo relative to theUAV based on an angle of the cable.
 8. The method of claim 1, whereinthe UAV is initially adjacent the cargo on land, and wherein operatingthe at least four laterally-arranged rotors to elevate the UAV to aninitial operating height comprises elevating the UAV initiallyvertically in an upward direction followed by flying the UAV in ahorizontal or angled direction toward the cargo, such that the UAVhovers above the cargo at the initial operating height.
 9. The method ofclaim 1, wherein the predetermined length of the sling cable is at least25 feet.
 10. A transport system comprising: a UAV having at least fourlaterally-arranged rotors; one or more sensors on the UAV configured todetect an angular position of cargo relative to an underside of the UAV;an attachment device affixed to the underside of the UAV and configuredto releasably couple to a first portion of a cable having apredetermined length and being secured to the cargo at a second portionof the cable; and one or more processors configured to executeinstructions stored in memory to perform functions of: opening aretaining latch on the attachment device to receive the first portion ofthe cable; and closing the retaining latch to couple the first portionof the cable to the attachment device; operating the at least fourlaterally-arranged rotors to cause the UAV to elevate to an initialoperating height, the initial operating height being less than thepredetermined length of the cable such that that UAV does not supportthe cargo; determining, via the one or more sensors, that the UAV ispositioned within a predetermined region above the cargo; and responsiveto determining that the UAV is positioned within the predeterminedregion above the cargo, operating the at least four laterally-arrangedrotors to elevate the UAV to a second height that is greater than theinitial operating height and controlling the UAV to navigate to a targetlocation.
 11. The transport system of claim 10, wherein the one or moresensors comprises a rotary variable inductance transducer (RVIT). 12.The transport system of claim 11, wherein a position of the cargo iscalculated relative to the UAV based on an angular position of thecable.
 13. The transport system of claim 10, the functions furthercomprising: determining that the UAV is at the target location andreceiving a release command; and responsive to the determination thatthe UAV is at the target location and receiving the release command,releasing the first portion of the cable from the attachment device. 14.The transport system of claim 10, the functions further comprising:defining a mission profile that comprises a plurality of predeterminedcontingent landing sites along a travel path to the target location,wherein the predetermined contingent landing sites each comprise a cargorecovery system.
 15. The transport system of claim 14, the functionsfurther comprising: determining to execute a contingent landing at oneof the plurality of predetermined contingent landing sites; responsiveto the determination, releasing the cargo; and proceeding to fly to andland at a contingent landing site of the plurality of predeterminedcontingent landing sites.
 16. The transport system of claim 10, whereinthe predetermined length is at least 25 feet.
 17. The transport systemof claim 10, wherein the attachment device is configured to send signalsto the one or more processors indicating whether the attachment deviceis open or closed.
 18. The transport system of claim 10, wherein theattachment device is coupled to one or more legs that are attached tothe underside of the UAV.
 19. The transport system of claim 10, whereinthe cable is a sling cable comprising a plurality of lateral arrestingcable portions between the first portion and the second portion whichserve to connect to another cable to prevent interference of the slingcable with a landing gear of the UAV.
 20. A control system forcontrolling transport of a cargo, the control system comprising one ormore processors configured to execute instructions stored in memory toperform functions of: coupling at least one electronically-controllableattachment device positioned below an underside of a UAV to a firstportion of a sling cable; operating at least four laterally-arrangedrotors to cause the UAV to take-off and navigate to (i) a positionwithin a predetermined area above the cargo, and (ii) an initialoperating height, the initial operating height being less than apredetermined length of the sling cable such that the UAV does notsupport the cargo; determining that the UAV is positioned within apredetermined area above the cargo; and responsive to determining thatthe UAV is positioned within a predetermined area above the cargo,operating the at least four laterally-arranged rotors to elevate the UAVto a second height that is greater than the initial operating height andcontrolling the UAV to navigate to a target location.